DE102005032141B4 - Method and device for determining the irradiation field strength in an aircraft - Google Patents

Abstract

Method for determining the irradiation field strength in an aircraft and influencing an electrical system in the aircraft with cables (6) between an outer skin (2) and an inner lining (3) of the aircraft fuselage (1) for transmitting signals within the aircraft, comprising the steps:
Either coupling a predetermined transmission signal into at least one leakage line (7) between the outer skin (2) and the inner lining (3) of the aircraft fuselage (1) and receiving the received signal emitted by the leakage line with a receiver (10, 10a),
• or transmitting a predetermined transmission signal by a transmitter (8) and decoupling the received signal from the leakage line (7) and
Comparing the amplitudes of the transmission signal and the reception signal.

Description

The The invention relates to the protection of an electrical transmission system or by such a transmission system interconnected electronic components in an aircraft electromagnetic radiation. In particular, the invention relates a method and an apparatus for determining the irradiation field strength in one Aircraft according to the preamble of claim 1 or claim 3.

The Wiring in vehicles and in particular in aircraft is in usually between the outer skin of the vehicle and an interior trim of the vehicle. Under cabling here are all electrically conductive cable for transmission understood by electrical signals and for power. The shell of aircraft is generally made of metal and thus provides a good electrical shielding to the outside, so the wiring only slightly is affected by electrical radiation from the outside.

Around the aircraft wiring from being influenced by electromagnetic To protect the radiation from the inside, For example, electromagnetic fields generated by mobile phones Of the passengers are emitted, many of the cables are in the plane shielded, i. individual lines or even entire trunk group are wrapped with metallic braided shields. In addition, the lines often twisted as well.

The Shielding of the cables carries however, significantly add to the weight of the aircraft. Would you let go of the shielding a weight saving of up to approx. 150 kg can be achieved. At the However, the prior art described above would go by the Protection against radiation lost, and electromagnetic radiation could be the Function of the electronic system of the aircraft, i. the function the individual electronic components and the transmission network directly affect.

Out EP 0 915 577 a system is known for the use of mobile phones in a commercial aircraft, which are operable in a particular working according to the GSM standard cellular mobile network with multiple base stations and their transmission power is controlled via the base stations, provided on board the aircraft, a base station of the associated mobile network is, which is connected via a radio transmission link with the associated ground-based mobile network. The base station automatically reduces the transmitter power of a mobile phone activated in the aircraft to a minimum.

Out DE 197 04 763 is a method for detecting high-frequency electromagnetic radiation from the air vehicle interior known for electromagnetic radiation predominantly poorly permeable Lufffahrzeughülle. In this method, the electromagnetic radiation outside the aircraft airframe is detected by at least one outdoor sensor, the electromagnetic radiation within the airframe is detected by at least one internal sensor, the output values associated with the outdoor sensor are compared with the initial values associated with the internal sensor, and a comparison value is formed. On the basis of the comparison value, an emission of an interfering radiation within the air vehicle casing is concluded and a corresponding message signal is generated.

task The present invention is to provide a device and to provide a method with which the irradiation field strength in an aircraft can be checked easily and reliably and thus the electromagnetic susceptibility of the electrical system can be reduced in the aircraft.

These The object is achieved by the method of claim 1 and the electrical transmission system according to claim 3. Preferred embodiments The invention are the subject of the dependent claims.

Of the Invention is based on the idea, a leakage line as a radiator between the outer skin and the interior trim and their transmission and reception behavior to investigate. Preferably, the leakage line becomes near critical Points and substantially parallel to existing lines in the aircraft installed to the transmission and reception behavior of the existing To simulate lines. To the transmission behavior of the existing lines To investigate, a signal from a test transmitter is coupled into the leakage line. The signal emitted by the leakage line is transmitted by a mobile receiver received within the aircraft. To the reception behavior of Existing lines will be examined by a test transmitter inside or outside of Aircraft emitted a test signal and the signal strength of the Measured in the leakage line received test signal. This will be created a measuring system that provides information about the susceptibility of the electrical system in the aircraft with high accuracy and reproducibility allows and which has very stable electrical properties.

• • entweder Einkoppeln eines vorgegebenen Sendesignals in wenigstens eine Leckleitung zwischen der Außenhaut und der Innenverkleidung des Flugzeugrumpfes und Empfangen des von der Leckleitung abgestrahlten Empfangssignals mit einem Empfänger,
• • oder Senden eines vorgegebenen Sendesignals durch einen Sender und Auskoppeln des Empfangssignals aus der Leckleitung und

Vergleichen der Amplituden des Sendesignals und des Empfangssignals.The inventive method for determining the irradiation field strength in an aircraft and influencing an electrical Sys Tems in the aircraft with electrical cables between an outer skin and an inner lining of the fuselage for transmitting signals within the aircraft comprises the steps:

• Either coupling a predetermined transmission signal into at least one leakage line between the outer skin and the inner lining of the aircraft fuselage and receiving the reception signal emitted by the leakage line with a receiver;
• • or sending a predetermined transmission signal by a transmitter and decoupling the received signal from the leakage line and

Comparing the amplitudes of the transmission signal and the reception signal.

Preferably be in the inventive method additionally compared the amplitudes of measured values with and without inner lining. This can be done by taking the difference or quotient of the respective one Measured values happen.

• • entweder der Sender mit der Leckleitung verbunden ist zum Einkoppeln des vorgegebenen Sendesignals in die Leckleitung und Empfangen des von der Leckleitung abgestrahlten Empfangssignals mit dem Empfänger,
• • oder der Empfänger mit der Leckleitung verbunden ist zum Auskoppeln des Empfangssignals von der Leckleitung und

einen Vergleicher zum Vergleichen der Amplituden des Sendesignals und des Empfangssignals.Accordingly, the electrical transmission system according to the invention in an aircraft with electrical cables between an outer skin and an inner lining of the fuselage for transmitting electrical signals within the aircraft with a device for determining the irradiation field strength in an aircraft is characterized marked by at least one leakage line between the outer skin and the inner lining the aircraft fuselage, at least one transmitter for transmitting a predetermined transmission signal and at least one receiver for receiving a radiated received signal, wherein

• Either the transmitter is connected to the leakage line for coupling the predetermined transmission signal into the leakage line and receiving the reception signal emitted by the leakage line with the receiver,
• • or the receiver is connected to the leakage line for decoupling the received signal from the leakage line and

a comparator for comparing the amplitudes of the transmission signal and the reception signal.

The electrical system according to the invention preferably has one or, as far as possible, several of the following features:
the comparator is a quadrupole analyzer;
the receiver comprises a leakage line as an antenna, which is in particular a coaxial line, or
the receiver comprises a mobile antenna whose geometrical extent is small compared to the longitudinal extent of the leakage line. In particular, the antenna in this embodiment of the invention is a broadband monopole antenna having an extension of approximately 25 cm × 25 cm for the frequency range between a few MHz and a few GHz.

One Advantage of the invention is that the main Difficulties in arranging suitable antennas in the aircraft to control the electromagnetic shielding effect of wall coverings overcome in the installed state become. The panels that make up the interior lining, are used better and more effectively. Any kind of maintenance, at which the interior lining has to be attached, removed or rebuilt becomes simplified and thus cheaper.

Further Features and advantages of the invention will become apparent from the following DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG is attached to the Drawing.

1 shows an aircraft fuselage in cross-section with the device according to the invention.

2 shows in perspective a part of the inner lining in the fuselage with the device according to the invention.

The Representation in the drawings is not to scale. Same or same acting elements are provided with the same reference numerals.

In 1 is a fuselage 1 shown in cross section in a plane which is perpendicular to the longitudinal axis of the aircraft. The fuselage 1 has an outer skin 2 on. In the fuselage is a cargo hold for goods or a passenger cabin for air travelers. The cargo compartment or the cabin is with an interior lining or interior lining 3 clad, which consists for example of individual panels of glass fiber reinforced plastic. This protects the interior against temperature fluctuations, pollution, noise and condensation.

Depending on the type of aircraft, the floor of the cabin or cargo space is a floor support structure 4 strengthened. The interior usually does not extend up to the outer skin 2 of the plane, but ends in a roof structure 5 with (not shown) supply lines, which are intended for the supply between the bow and stern of the aircraft.

In the space between the outer skin 2 of the plane and the formwork 3 are electrical transmission cables 6 for communication within the aircraft. This transmission cable 6 can be used to transfer control commands from the cockpit to the wings or to the rudder, or to transfer information between the cockpit crew and persons in the cockpit Cargo space can be exchanged.

If electromagnetic waves penetrate into the interior of the aircraft, it may interfere with the signals on the transmission cables 6 come so that the communication within the aircraft is impaired or the transmission of important data is even interrupted.

If the shielding of each cable 6 is removed to save weight, and instead the entire interior trim 3 of the aircraft is provided with a conductive layer, it must be ensured that when working on the interior trim 3 the shielding of the interior trim is restored to its original state after completion of the work and satisfies the requirements for electromagnetic damping. For this purpose, according to the invention between the wall paneling 3 and the outer skin 2 of the aircraft installs an antenna. This antenna is a cable that acts as a transmitting and / or receiving antenna. The cable is preferably placed in the vicinity of those transmission cables that are particularly prone to failure. In particular, the antenna is a leakage line. This leakage line is in principle a coaxial line. It consists of an insulated central conductor, which is surrounded by an electrical shielding braid or copper tube. In normal coaxial cables, this shielding is made so tight that as high as possible no high frequency energy can penetrate it. This has the effect that the high-frequency power to be transmitted is not weakened by the fact that power can escape through the screen. Likewise, the screen prevents external high frequency fields from entering the cable. Coaxial cables are characterized by largely stable and frequency-independent electrical properties. In the case of a leakage line, this screen is now deliberately designed so that it becomes permeable to a certain extent for the high-frequency energy. The lead largely retains its good electrical properties, but a controlled portion of the conducted RF energy penetrates out through the shield and is radiated into the environment. The line acts like a spatially extended transmitting antenna. On the other hand, external fields can now penetrate into the cable. It also acts as a spatially extended receiving antenna. Depending on the constructive design of the shield, the field component that penetrates the shield can be set well.

The Leakage is preferably permanently installed - like a normal transmission cable - and stands with e.g. after maintenance work on the wall cladding at any time for measurements to disposal.

The measurement method is described below with reference to 2 explained.

In 2 is the interior lining or interior cladding 3 (Protective lining) of the cargo compartment or the cabin without outer shell shown in perspective. As can be seen, the inner casing is set 3 from several individual panels 3a together. Some of the panels 3a can be located near windows or hatches of the aircraft so they have breakthroughs 3b at the level of the respective windows and openings in the outer skin of the aircraft. In order to minimize the irradiation field strength in an aircraft on the electric cables and thus the influence of the electrical system in the aircraft with transmission cables 6 between the outer skin 2 and the interior formwork 3 of the fuselage 1 to reduce the transmission of signals within the aircraft, the inner lining of the cargo or passenger compartment is provided with an electrically conductive coating which performs the shielding function, which has been met in the prior art by the individual shielding of the cable. This avoids that the aircraft cabling is affected by electromagnetic fields from the interior of the aircraft, for example, by electromagnetic fields emitted by the cell phones of passengers or electromagnetic fields that pass through an open hatch into the interior of the aircraft.

The interior paneling 3 is composed of a multitude of panels. The panels are all individually conductive coated and then joined together. This means that certain minimum electrical resistance requirements must be met by both the coating of the individual panels and the electrical connection of the panels to each other, resulting in a Faraday cage. For this purpose, a very large number of so-called contact elements may be provided, or the coating of the panels is continued over the seams between the individual panels. The contact elements are fulcrums on a panel to which a wire connection or other electrical connection can be made to terminate at a corresponding fulcrum on an adjacent panel. By such a wire bridge between two coated panels, the electrical resistance between the two panels is made very small. Alternatively, the contact elements may be rivets or similar mechanical fasteners that are themselves electrically conductive and that pass through two adjacent panels, thereby establishing electrical contact between the panels.

The openings and windows 3b in the pane len 3 are closed by inserts, not shown, which are coated as well as the rest of the respective panels. This can also be through the openings and windows 3b in the panels no electromagnetic radiation penetrate unhindered into or out of the aircraft.

in the Quality assurance framework during the construction of the aircraft as well as later in the aircraft maintenance has to be checked, that the required protective effect of the shield is achieved and is always adhered to, even after a possible later processing the coated panels. This would require the electrical resistance at the transition be measured between each two adjacent panels. This But in practice it is not possible even if instead of a continuous one Coating individual contact elements inserted between the panels because the number of contact elements is much too large. you but can this exam so perform that one the easing an electromagnetic wave that passes through the inner lining is sent through. Therefore needed you have a suitable antenna arrangement that allows electromagnetic Waves in a reproducible way through the finished interior lining to send and determine the weakening that occurs.

This is inventively achieved in that the attenuation of electromagnetic waves is detected by all coated panels in a single measurement step. For this purpose, the wall cladding is placed between a transmitting and a receiving antenna, and the attenuation is measured with a suitable measuring device, such as a quadrupole analyzer. The difference between the measured values with and without wall cladding results in the desired screening effect of the wall cladding 3 ,

The transmitting or receiving antenna according to the invention is a permanently installed leakage line 7 , It is located in particular in the vicinity of the actual transmission lines 6 of which, for the sake of clarity, only one in 2 is shown. Particularly preferably, the leakage line runs 7 parallel to the actual transmission lines 6 , The leakage line 7 does not represent a point-shaped radiation source, but generates over its length a well-dosed electromagnetic field, which is optionally evenly distributed. This is in 2 through two symbolic radiation beams 9 indicated. The leakage line 7 thus allows the detection of the attenuation of electromagnetic radiation through a significant portion of the wall paneling 3 ,

However, instead of a uniform distribution of the electromagnetic field, the course of the leakage line can also be adjusted according to the requirements of the actually detectable area. If necessary, it is also possible to use several leakage lines 7 to install. In any case, the leakage line 7 behind the wall cladding to be measured 3 arranged, ie the wall cladding 3 Located between a transmitting and a receiving antenna, which may be inside or outside the aircraft.

In the illustrated embodiment, the leakage line 7 from a transmitter 8th powered by a transmitter antenna feed 8a with the leakage line 7 connected is. The leakage line 7 emits and the radiated signal is from a receiver 10 via its receiving antenna 10a detected. Subsequently, the two amplitudes of the transmission signal and the received signal are evaluated and in a comparator 11 , via comparator leads 11a with the transmitter 8th or receiver 10 connected, compared. The result is communicated to the user via input / output devices, not shown, so that the user observes the attenuation values through the interior lining 3 even after machining or servicing the interior trim 3 can check.

In addition, it is possible, via the simple comparison of the transmitted signal and the received signal, the measured values also with previously stored values without wall cladding 3 to compare. In this way, one obtains a comparison value, which refers to, for example, an absolute scale, and not a comparison value, which refers to a relative scale.

The comparator 11 is preferably a quadrupole analyzer. The actual comparison can be made, inter alia, on the basis of a difference or a quotient of the measured values. The antenna 10a Recipient 10 may be a (not shown) leakage line, in its orientation and extent substantially the permanently installed leakage line 7 equivalent. In particular, the leakage line may be a coaxial line, which is prepared in a similar way as leakage line as the permanently installed leakage line 7 ,

Alternatively, the antenna 10a Recipient 10 to be a mobile antenna. In this case, one can use the mobile receiving device to target the interior of the aircraft for leaks in the wall shield 3 scan. The mobile antenna is characterized in that its dimensions compared to the longitudinal extent of the leakage line 7 are small. For example, the mobile antenna has an extension of about 25 cm × 25 cm, making it particularly suitable for the frequency range between a few MHz and a few GHz.

Due to the previous description is It is clear to the person skilled in the art that the transmitter and the receiver can be exchanged. Instead of the transmission signal in the leakage line 7 between the outer skin 2 and the interior formwork 3 of the fuselage 1 is coupled and that of the leakage line 7 radiated received signal with the receiver 10 is received, the transmission signal by the transmitter 8th via a rod antenna or the like and the received signal from the receiver 10 from the leakage line 7 be decoupled, which via a corresponding line with the leakage line 7 connected is.

In the case of measuring the shielding of the interior of the aircraft through the wall cladding 3 is the receiving antenna 10a preferably approximately on the (not shown) longitudinal axis of the aircraft cabin. The receiving antenna can also be realized by a leakage line or alternatively as a mobile antenna, the geometric extent is small compared to the longitudinal extent of the leakage line 7 and which is a broadband monopole antenna with an extension of about 25 cm x 25 cm, which is optimized for the frequency range between a few MHz and a few GHz.

1

fuselage

2

shell

3

Inner casing, 3a panels, 3b Window opening in panel

4

Ground support structure

5

roof structure

6

transmission cable

7

leakage line

8th

Transmitter, 8a Transmitter antenna feed

9

electromagnetic radiation

10

Receiver, 9a receiving antenna

11

comparator, 11a Vergleicherzuleitung

Claims (7)

Method for determining the irradiation field strength in an aircraft and influencing an electrical system in the aircraft with cables ( 6 ) between an outer skin ( 2 ) and an interior lining ( 3 ) of the fuselage ( 1 ) for transmitting signals within the aircraft comprising the steps of: • either coupling a predetermined transmission signal into at least one leakage line ( 7 ) between the outer skin ( 2 ) and the interior trim ( 3 ) of the fuselage ( 1 ) and receiving the emitted from the leakage line received signal with a receiver ( 10 . 10a ), Or • sending a given transmission signal by a transmitter ( 8th ) and decoupling the received signal from the leakage line ( 7 ) and comparing the amplitudes of the transmission signal and the reception signal. Method according to claim 1, wherein additionally the Amplitudes of readings compared with and without interior trim become. Electric transmission system in an airplane with cables ( 6 ) between an outer skin ( 2 ) and an interior lining ( 3 ) of the fuselage ( 1 ) for transmitting signals within the aircraft with a device for determining the irradiation field strength in an aircraft, characterized by at least one leakage line ( 7 ) between the outer skin ( 2 ) and the interior trim ( 3 ) of the fuselage ( 1 ), at least one transmitter ( 8th . 8a ) for transmitting a predetermined transmission signal and at least one receiver ( 10 . 10a ) for receiving a radiated received signal, wherein • either the transmitter ( 8th . 8a ) is connected to the leakage line for coupling the predetermined transmission signal in the leakage line, • or the receiver ( 10 . 10a ) is connected to the leakage line for decoupling the received signal from the leakage line and a comparator ( 11 ) for comparing the amplitudes of the transmission signal and the reception signal. Electrical transmission system according to claim 3, in which the comparator ( 11 ) is a quadrupole analyzer. Electrical transmission system according to claim 3 or 4, in which the receiver ( 10 ) a leakage line as antenna ( 10a ). Electrical transmission system according to one of claims 3 or 4, in which the receiver ( 10 ) comprises a mobile antenna whose geometrical extent is small compared to the longitudinal extent of the leakage line ( 7 ). Electric transmission system according to one of the claims 3 to 6, wherein the at least one leakage line is a coaxial line is.